It is well known that various materials (including genetic materials) will luminesce under certain conditions and emit light at a wavelength with a variable intensity that is characteristic of the material. The nature of this so-called "light-off", however, is dependent on the particular assay which is used and the alacrity with which the assay is accomplished. Accordingly, by using precise timing in a procedure for a particular assay, the resulting luminescence from a sample material will give meaningful information about the concentration and constituency of the sample material.
In order for a sample material to luminesce and emit a light-off, the material is exposed to specific reagents according to a selected assay. After exposure of the material to these reagents, an increase in luminescence results from whatever steady state luminescence may be inherent in the material. Typically, this increased luminescence is characterized by a relatively rapid rise in the intensity of the light that is emitted from the sample. This rise is then immediately followed by a relatively slower return to ambient light intensity. Thus, emission intensity is typically represented by a curve having a skewed peak. For most materials, such a light-off occurs within a time period of approximately two (2) seconds.
To ascertain meaningful information about the sample material, it has been necessary for prior art luminometers to count photons and continuously integrate the intensity of the luminescence over a period of time to obtain a value which could be used for quantifying the sample. Since the light-offs obtained by perviously used assays were of particularly low intensity, and consequently difficult to read, the earlier luminometers necessarily incorporated high-cost precision components in order to detect this luminescence.
It has happened that improved assays are now giving better, and hence more readable, light-offs. Also, under certain circumstances, even the steady state luminescence after the light-off can be useful for analysis. As a consequence, the more sophisticated equipment which was required in the past to accurately record and profile a light-off for diagnostic purposes can now be replaced by less sophisticated equipment. Indeed, the present invention recognizes this can be done without any meaningful loss in the quality of the assay results.
In light of the above, it is an object of the present invention to provide a luminometer which can accurately sample the luminescence from a sample material for diagnostic purposes. Yet another object of the present invention is to provide a luminometer which can refine assay results by excluding background light from the luminescent signal that is descriptive of a sample's constituent concentration. Still another object of the present invention is to provide a luminometer that can be used for different assays. Finally, it is an object of the present invention to provide a luminometer which is relatively easy to use and comparatively cost-effective.